Yamaha YN 50 F Neos 4 (4T) 09 Valve Shim 1.55 mm
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- Spark Plug Basics
- What do the symbols on an NGK spark plug mean?
- Plug Types
- Hot and Cold Plugs
- Spark Plug Problems
- Fouling and Pre-Ignition
- How to Install
- Spark Plug Tools
Spark Plug Basics
The spark plug has two primary functions:
- 1 - Ignite air/fuel mixture
- 2 - Transfer heat from the combustion chamber
Spark plugs carry electrical energy and turn fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to spark across the spark plug's gap. This is called "Electrical Performance." The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called "Thermal Performance", and is determined by the heat range selected.It's important to remember spark plugs do not create heat, they only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat.